RSH(1) BSD General Commands Manual RSH(1)NAME
rsh — remote shell
SYNOPSIS
rsh [-45FGKdefnuxz] [-U string] [-p port] [-l username] [-P N|O] host
[command]
DESCRIPTION
rsh authenticates to the rshd(8) daemon on the remote host, and then exe‐
cutes the specified command.
rsh copies its standard input to the remote command, and the standard
output and error of the remote command to its own.
Valid options are:
-4, --krb4
The -4 option requests Kerberos 4 authentication. Normally all
supported authentication mechanisms will be tried, but in some
cases more explicit control is desired.
-5, --krb5
The -5 option requests Kerberos 5 authentication. This is analo‐
gous to the -4 option.
-K, --broken
The -K option turns off all Kerberos authentication. The security
in this mode relies on reserved ports. The long name is an indi‐
cation of how good this is.
-n, --no-input
The -n option directs the input from the /dev/null device (see
the BUGS section of this manual page).
-d Enable setsockopt(2) socket debugging.
-e, --no-stderr
Don't use a separate socket for the stderr stream. This can be
necessary if rsh-ing through a NAT bridge.
-x, --encrypt
The -x option enables encryption for all data exchange. This is
only valid for Kerberos authenticated connections (see the BUGS
section for limitations).
-z The opposite of -x. This is the default, and is mainly useful if
encryption has been enabled by default, for instance in the
appdefaults section of /etc/krb5.conf when using Kerberos 5.
-f, --forward
Forward Kerberos 5 credentials to the remote host. Also settable
via appdefaults (see krb5.conf).
-F, --forwardable
Make the forwarded credentials re-forwardable. Also settable via
appdefaults (see krb5.conf).
-l string, --user=string
By default the remote username is the same as the local. The -l
option or the username@host format allow the remote name to be
specified.
-n, --no-input
Direct input from /dev/null (see the BUGS section).
-p number-or-service, --port=number-or-service
Connect to this port instead of the default (which is 514 when
using old port based authentication, 544 for Kerberos 5 and non-
encrypted Kerberos 4, and 545 for encrytpted Kerberos 4; subject
of course to the contents of /etc/services).
-P N|O|1|2, --protocol=N|O|1|2
Specifies the protocol version to use with Kerberos 5. N and 2
select protocol version 2, while O and 1 select version 1. Ver‐
sion 2 is believed to be more secure, and is the default. Unless
asked for a specific version, rsh will try both. This behaviour
may change in the future.
-u, --unique
Make sure the remote credentials cache is unique, that is, don't
reuse any existing cache. Mutually exclusive to -U.
-U string, --tkfile=string
Name of the remote credentials cache. Mutually exclusive to -u.
-x, --encrypt
The -x option enables encryption for all data exchange. This is
only valid for Kerberos authenticated connections (see the BUGS
section for limitations).
-z The opposite of -x. This is the default, but encryption can be
enabled when using Kerberos 5, by setting the libdefaults/encrypt
option in krb5.conf(5).
EXAMPLES
Care should be taken when issuing commands containing shell meta charac‐
ters. Without quoting, these will be expanded on the local machine.
The following command:
rsh otherhost cat remotefile > localfile
will write the contents of the remote remotefile to the local localfile,
but:
rsh otherhost 'cat remotefile > remotefile2'
will write it to the remote remotefile2.
FILES
/etc/hosts
SEE ALSOrlogin(1), krb_realmofhost(3), krb_sendauth(3), hosts.equiv(5),
krb5.conf(5), rhosts(5), kerberos(8)rshd(8)HISTORY
The rsh command appeared in 4.2BSD.
AUTHORS
This implementation of rsh was written as part of the Heimdal Kerberos 5
implementation.
BUGS
Some shells (notably csh(1)) will cause rsh to block if run in the back‐
ground, unless the standard input is directed away from the terminal.
This is what the -n option is for.
The -x options enables encryption for the session, but for both Kerberos
4 and 5 the actual command is sent unencrypted, so you should not send
any secret information in the command line (which is probably a bad idea
anyway, since the command line can usually be read with tools like
ps(1)). Forthermore in Kerberos 4 the command is not even integrity pro‐
tected, so anyone with the right tools can modify the command.
HEIMDAL February 20, 2004 HEIMDAL
